/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the  "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id$
 */
package wx.xml.xalan.xalan.transformer;

import java.util.Hashtable;
import java.util.Vector;

import javax.xml.transform.TransformerException;

import wx.xml.xalan.xalan.templates.ElemNumber;
import wx.xml.xalan.xml.dtm.DTM;
import wx.xml.xalan.xpath.NodeSetDTM;
import wx.xml.xalan.xpath.XPathContext;

/**
 * This is a table of counters, keyed by ElemNumber objects, each
 * of which has a list of Counter objects.  This really isn't a true
 * table, it is more like a list of lists (there must be a technical
 * term for that...).
 *
 * @xsl.usage internal
 */
public class CountersTable extends Hashtable {
    static final long serialVersionUID = 2159100770924179875L;
    /**
     * Number of counters created so far
     */
    transient int m_countersMade = 0;
    /**
     * Place to collect new counters.
     */
    transient private NodeSetDTM m_newFound;

    /**
     * Construct a CountersTable.
     */
    public CountersTable() {
    }

    /**
     * Get the list of counters that corresponds to
     * the given ElemNumber object.
     *
     * @param numberElem the given xsl:number element.
     * @return the list of counters that corresponds to
     * the given ElemNumber object.
     */
    Vector getCounters(ElemNumber numberElem) {

        Vector counters = (Vector) this.get(numberElem);

        return (null == counters) ? putElemNumber(numberElem) : counters;
    }

    /**
     * Put a counter into the table and create an empty
     * vector as it's value.
     *
     * @param numberElem the given xsl:number element.
     * @return an empty vector to be used to store counts
     * for this number element.
     */
    Vector putElemNumber(ElemNumber numberElem) {

        Vector counters = new Vector();

        this.put(numberElem, counters);

        return counters;
    }

    // For diagnostics

    /**
     * Add a list of counted nodes that were built in backwards document
     * order, or a list of counted nodes that are in forwards document
     * order.
     *
     * @param flist Vector of nodes built in forwards document order
     * @param blist Vector of nodes built in backwards document order
     */
    void appendBtoFList(NodeSetDTM flist, NodeSetDTM blist) {

        int n = blist.size();

        for (int i = (n - 1); i >= 0; i--) {
            flist.addElement(blist.item(i));
        }
    }

    /**
     * Count forward until the given node is found, or until
     * we have looked to the given amount.
     *
     * @param support    The XPath context to use
     * @param numberElem The given xsl:number element.
     * @param node       The node to count.
     * @return The node count, or 0 if not found.
     * @throws TransformerException
     */
    public int countNode(XPathContext support, ElemNumber numberElem, int node)
        throws TransformerException {

        int    count     = 0;
        Vector counters  = getCounters(numberElem);
        int    nCounters = counters.size();

        // XPath countMatchPattern = numberElem.getCountMatchPattern(support, node);
        // XPath fromMatchPattern = numberElem.m_fromMatchPattern;
        int target = numberElem.getTargetNode(support, node);

        if (DTM.NULL != target) {
            for (int i = 0; i < nCounters; i++) {
                Counter counter = (Counter) counters.elementAt(i);

                count = counter.getPreviouslyCounted(support, target);

                if (count > 0)
                    return count;
            }

            // In the loop below, we collect the nodes in backwards doc order, so
            // we don't have to do inserts, but then we store the nodes in forwards
            // document order, so we don't have to insert nodes into that list,
            // so that's what the appendBtoFList stuff is all about.  In cases
            // of forward counting by one, this will mean a single node copy from
            // the backwards list (m_newFound) to the forwards list (counter.m_countNodes).
            count = 0;
            if (m_newFound == null)
                m_newFound = new NodeSetDTM(support.getDTMManager());

            for (; DTM.NULL != target;
                 target = numberElem.getPreviousNode(support, target)) {

                // First time in, we should not have to check for previous counts,
                // since the original target node was already checked in the
                // block above.
                if (0 != count) {
                    for (int i = 0; i < nCounters; i++) {
                        Counter counter  = (Counter) counters.elementAt(i);
                        int     cacheLen = counter.m_countNodes.size();

                        if ((cacheLen > 0)
                            && (counter.m_countNodes.elementAt(cacheLen
                            - 1) == target)) {
                            count += (cacheLen + counter.m_countNodesStartCount);

                            if (cacheLen > 0)
                                appendBtoFList(counter.m_countNodes, m_newFound);

                            m_newFound.removeAllElements();

                            return count;
                        }
                    }
                }

                m_newFound.addElement(target);

                count++;
            }

            // If we got to this point, then we didn't find a counter, so make
            // one and add it to the list.
            Counter counter = new Counter(numberElem, new NodeSetDTM(support.getDTMManager()));

            m_countersMade++;  // for diagnostics

            appendBtoFList(counter.m_countNodes, m_newFound);
            m_newFound.removeAllElements();
            counters.addElement(counter);
        }

        return count;
    }
}
